1. Field of the Invention
The invention relates to a delivery system for agriculturally active chemicals, and, more particularly, to an inert matrix composition for forming a microemulsion concentrate and an aqueous microemulsion of a pyrethroid insecticide.
2. Definitions
As used herein, the following terms have the meanings indicated:
(a) "Microemulsion" means an oil-in-water or water-in-oil, transparent thermodynamically stable dispersion of two or more immiscible liquids wherein the dispersed phase consists of small droplets with diameters in the range of about 10 to 100 millimicrons. Such microemulsions are clear and contain at least about 80% by weight water.
(b) "Macroemulsion" means an emulsion of water-in-oil or oil-in-water wherein the interior phase is in the form of visually discernable droplets and the overall emulsion is cloudy, and wherein the droplet diameter is greater than about 100 millimicrons.
(c) "Clear" or "Transparent" as applied to a microemulsion means that the composition appears as a single phase without any particulate or colloidal material or a second phase being present when viewed by the naked eye.
(d) "Substantially Insoluble" or "Insoluble" means that for all practical purposes, the solubility of the compound in water is insufficient to make the compound practicably usable in an agricultural end use without some modification either to increase its solubility or dispersability in water, so as to increase the compound's bioavailability or avoid the use of excessively large volumes of solvent.
(e) "High Degree of Loading" in a microemulsion concentrate means an agriculturally active ingredient content of at least about 5 percent by weight.
(f) The term "Agriculturally Active Chemical or Ingredient" (AAC) means compounds and mixtures thereof which can be used as agricultural fertilizers, nutrients, plant growth accelerants, herbicides, plant growth controlling chemicals, and chemicals which are effective in killing plants, insects, microorganisms, fungi, bacteria and the like which are commonly referred to as insecticides, bactericides, fungicides, nematocides, fumigants, synergists, i.e., compounds which when used in conjunction with other AAC's enhance their activity and the like, as well as any other chemicals having properties which are suitable for agricultural uses in terms of application to plants or domestic uses for controlling insects and pests.
(g) "Synthetic Pyrethroid" is an AAC such as organic compounds having the formulas:
(.+-.) alpha-cyano-3-phenoxybenzyl (.+-.) cis, trans 3-(2,2-dichlorovinyl)-2,2-dimethyl cyclopropane carboxylate; PA0 (RS)-3-allyl-2-methyl-4-oxocyclopent-2-enyl (1RS)-cis, trans-chrysanthemate; PA0 3-phenoxybenzyl (1RS)-cis, trans-3-(2,d-dichlorovinyl)-2,2-dimethylcyclopropanecarboxylate; PA0 3,4,5,6-tetrahydrophthalimidomethyl (.+-.)-cis, transchrysanthemate); PA0 5-[2-(2-*butoxyethoxy)ethoxymethyl]-6-propyl-1,3-benzodioxole; FNT * this compound is a known synergist for synthetic pyrethroids PA0 (RS)-alpha-cyano-3-phenoxybenzyl 2,2,3,3-tetramethylcyclopropanecarboxylate; and PA0 (.+-.) cyano (3-phenoxyphenyl methyl (.+-.)-4-(difluoromethyoxy) alpha-(1-methylethyl) benzene acetate.
Commercial synthetic pyrethroid insecticides include D-allethrin, permethrin, tetramethrin and kathon, alone, or as complex mixtures, with and without synergists, such as piperonyl butoxide**, or other AAC ingredients, such as 2N-octyl-4-isothiazdin-3-one and propaconazole. FNT ** 3,4-methylenedioxy-6-propyl benzyl n-butyl diethylene glycol ether
(h) "Inert Matrix Composition" (IMC)--a predetermined mixture of defined nonionic surfactants, optionally with one or more anionic surfactants, and/or with a C.sub.1 -C.sub.4 alkylpyrrolidone, e.g. N-methylpyrrolidone, which, upon admixture with a pyrethroid insecticide and water, will form a clear, efficacious, aqueous microemulsion which is stable at or below room temperature for an extended period of time.
(i) "Two-Part Microemulsion System" (TPMS)--as the first part, the IMC; as the second part, a pyrethroid insecticide; and, wherein, optionally, up to 60% by weight of a C.sub.1 -C.sub.4 alkylpyrrolidone, e.g. N-methylpyrrolidond, is present in said system as a component of either or both of said parts before admixture.
(j) "Microemulsion Concentrate" (MEC)--the admixture product of both parts of the TPMS.
(k) "Water-Based Microemulsion" (WBME) or "Aqueous Microemulsion" (AM)--The TPMS (0.5-20%) and water (80-99.5%), by weight.
(1) "Nonionic Surfactant" - Representative materials include:
(1) N-Alkylpyrrolidone (alkyl C.sub.6 -C.sub.18), e.g. N-octylpyrrolidone - (Surfadone LP-100 - ISP) PA1 (2) Ethylene oxide (EO)/propylene oxide (PO)/EO block copolymers, e.g. (2 EO/16 PO/2 EO--H.sub.2 O) - (Pegal L-31), and PA1 (3) Alkylphenol ethoxylated alcohol having an HLB.gtoreq.6, e.g. nonylphenol ethoxylated alcohol with 9 EOs - (Igepal CO-630). PA1 (m) "Anionic Surfactant" -- Representative materials include: Nonylphenol ethoxylated phosphate ester with 9 EOs Gafac RE-610. PA1 (n) "Cosolvent" -- An N-alkyl (C.sub.1 -C.sub.4) pyrrolidone -- representative materials include: N-Methylpyrrolidone (NMP).